This invention relates to a method of reducing oxides and more particularly to a method of reducing iron ores in a plasma arc torch.
Conventionally, steel has been produced by a process comprising: (1) producing coke in batteries of coke ovens, (2) converting iron ore into pig iron by reacting the ore with the coke in a blast furnace, and (3) refining the pig iron into steel in an open hearth, basic oxygen, or electric furnace. The investment to produce steel by this route is enormous and requires a large annual capacity to be economically feasible.
However, there is a need for steel plants of relatively small annual capacity, and the attempt to satisfy this need has led to the development of direct reduction processes in which iron ore is reduced without the use of a blast furnace.
One process for directly reducing ore comprises: (a) introducing a mixture of solid particles of ore and a reductant into a plasma arc torch, typically including a cathode and an anode, and (b) entraining the mixture in the arc. Although this process has been successful in converting, for example, iron ore to steel, the problems are: (1) relatively rapid erosion of the anode, (2 ) excessive heat losses in the anode region, and (3) relatively high power consumption and relatively low reductant utilization per unit of ore reduced.
The object of the present invention is to provide a plasma arc torch reduction process that provides improved performance in terms of these three points.